A lie detector test is also known or commonly referred to as a polygraph test or polygraph examination. During an examination manifestations of a person’s nervous system are recorded from at least three systems in the body whilst questioned about a specific issue, incident or event. The procedure is in-depth, consisting of four phases with the examination typically 2 to 3 hours in length. We use state of the art computerised polygraph systems, sensors and validated test techniques.
The four phases of a polygraph examination are referred to as the pre-test, chart collection, test data analysis and finally the post-test phase.
The pre-test phase will commence with the examinee completing a consent form and medical form. The examiner will then provide an overview of the examination and testing procedures. The examinee will then be given the opportunity to discuss their circumstance at length which assists the examiner with test question construction. It is therefore imperative to be truthful, open and honest with the examiner as any undisclosed information may affect the outcome of the test results.
Chart collection phase.
Two convoluted tubes are placed around the upper chest and abdomen to record respiratory activity. Two metal plates or disposable adhesive electrodes are attached to the examinees fingers to record sweat gland activity and a blood pressure cuff will record cardiovascular activity. A motion sensor will monitor general movements throughout the examination. A finger plethysmograph may also be used to monitor blood volume.
A review of the test questions will be carried out followed by the administration of several tests. The number of questions and tests administered will vary depending on the format of the test used and test technique.
Test data analysis phase.
On completion of the chart collection phase, the examiner will review the data collected and analyse the charts. An opinion of the examinee’s truthfulness regarding the specific issue, incident or event will then be rendered.
The examiner will provide the examinee with a verbal result and where appropriate the examiner will offer the examinee an opportunity to explain physiological responses to the questions presented during the test.